Construct a DFA, accepting all strings ending with 'ab' over ∑={a,b}

SOLUTION:

∑={a,b}

L = {ab, aab, bab, abab, aaab,……… }

Ø  So DFA can be Q={ q₀ , q₁ , q₂},∑={a,b}, q₀={ q₀},F={q₂} and δ is given by the table

1)Transition diagram:

   2)Transition Table:

Present State	Next State
	Input a	Input b
à q0	q1	q0
q1	q1	q2
* q2	q1	q0

  3)Transition function:

δ( q₀, a)= q₁     ,δ (q₀,b)= q₀

            δ( q₁, a)= q₁     ,δ (q₁,b)= q₂   

δ( q₂, a)= q₁     ,δ (q₂,b)= q₀